1. Field of the Invention
This invention relates to a charge pump circuit used in a power supply circuit for an integrated circuit and the like.
2. Description of the Related Art
The charge pump circuit is a circuit composed of charge transfer MOS transistors, a capacitor, a clock driver and other components. It converts an input electric potential into a positive high electric potential or a negative electric potential and outputs the converted electric potential. The charge pump circuit is widely used as a power supply circuit for an integrated circuit and the like.
Further information on the charge pump circuit is disclosed in Japanese Patent Application Publication No. 2003-33006, for example.
However, in some application in which the output of the charge pump circuit varies, ranging from a positive electric potential to a negative electric potential, there has been a problem that an unwanted forward current flows through a parasitic diode accompanying the charge transfer MOS transistor to increase a power consumption or to get a circuit using the charge pump circuit out of control.